SIEMENS C3m POST OFFICE TRIODES 1960S SUPERVALVE USED TESTED
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SIEMENS C3m POST OFFICE TRIODES 1960S SUPERVALVE USED TESTED SIEMENS C3m POST OFFICE TRIODES 1960S SUPERVALVE USED TESTED SIEMENS C3m POST OFFICE TRIODES 1960S SUPERVALVE USED TESTED SIEMENS C3m POST OFFICE TRIODES 1960S SUPERVALVE USED TESTED

SIEMENS C3m POST OFFICE TRIODES 1960S SUPERVALVE USED TESTED

  • £9.00

Only 6 left!

SIEMENS C3m POST OFFICE TRIODES 1960S SUPERVALVE USED TESTED
We have a small stock of these scarce 20V filament pentodes which are used tested and showing perfect emission.  For those who are unaware of these - the best valves ever made, a little about them below: -
These German post tubes were designed as a compromise free valve by engineers whose aim was to design the ideal valve and then let the tube Siemens, Valve  and Telefunken factories try to make it. The “ 3“ notation  indicates the third iteration of design and the range comprises, in order of introduction the C3m, followed by the C3g  and were sold ONLY to the German postal service for duty in telephone repeater amplifiers.  These valves are characterised by the following design features:-
  • Highest amplification
  • Lowest low noise
  • Lowest microphonic
  • Greater lifetime than commercial tubes
  • Stand-by possibility 
  • Metal shielding
  • Use triode connected with loss of gain but no distortion increase
  • Comprehensive data sheet
  • Optional: Individual series number on each tube
  • Zirconium getter blade incorporation for dynamic gas sorption.

 

The cost of these paragons of thermionic perfection in 1965 was 295DM…. which equates £100, all at a time when for the price of 30 of these fine valves, you could buy a decent semi!!!!!!!   

 Some users do not like their closed can shielded appearance, however, with a bit of care both the black shield and the base overlap can be removed leaving a valve that looks a little like an EF86 on steroids 

Generally with C3m and C3g it can be said they have the gain of a pentode, and distortion levels similar to the finest triodes at more than three times the level of gain.   As an example a C3m with a  gain of 78 allows driving of a 300B with less than 1V input sensitivity with 0.12% THD. In a few words - these are superb valves for hifi usage.  


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